Glaze Room InductionPosted: November 6, 2014
Induction to glaze room was hosted by Matt the ceramics technical demonstrator. It involved the proper use of glaze materials, health and safety protocol of the glaze room – including how to work the ventilation systems – how to look up glazes, glaze making methodology and some general rules and guidelines concerning glaze use for different clay bodies.
Always wear a respirator , plastic apron and latex gloves if needed.
No glaze down sink.
Label jars clearly with appropriate warning stickers and also label with name, date, glaze recipe.
Keep area clean, wipe down after use and return equipment clean and complete to where it came from.
General Glaze Making and Methodology
Basic Glaze – 100g powdered raw materials to 100ml of water to give a nice double cream viscosity.
More feldspar to clay body = More glossy glaze.
More clay body to feldspar = More matte glaze.
The glazed, once slaked in water then mixed, is then sieved to make it of even consistency, this gives a nice smooth even glaze that should fire and hold better than an un-sieved glaze. Some sieving can take a while with some types of glaze. 80 mesh glaze is good for most glazes, 100 mesh is good for very fine and even glaze. Higher grades are available. When glaze is in jar mix it thoroughly before applying as glazes settle.
Apply glaze with old brushes, sponges or stable brushes. Can also dip work, pour glaze or use different tools for different techniques. For the most consistently even glaze coating use the spray booth. Build up several very thin layers letting each dry in-between. Thickness of glaze on earthenware should be 0.5 – 1 mm thick, on stoneware a 1- 2 mm thickness of glaze is needed.
When glazing a vessel try to glaze it inside and out as a tension across the vessel surface is created when glaze is fired. Total coverage can help minimise risk of cracking.
Remember to clean glaze off vessel foot ring before firing or work can stick to kiln shelf.
Do not mix lead and copper heavy glazes for tableware or anything that is a food vessel. Acidic things like vinegar or orange juice can cause the heavy metals in certain glazes to sweat (?) – at any rate could be toxic.
The induction went well and I enjoyed learning about the facility, Matt is clear, methodical and extremely helpful and pleasant. I feel happy to go and start experimenting with glaze making, I have made some glaze pieces from stoneware (St Thomas White) to experiment on.